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tls: in AES-GCM decoding, avoid memmove

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function                                             old     new   delta
xorbuf3                                                -      36     +36
xorbuf                                                24      12     -12
tls_xread_record                                     656     634     -22
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/2 up/down: 36/-34)              Total: 2 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-11-24 13:51:46 +01:00
parent 985702c892
commit 941440cf16
4 changed files with 17 additions and 15 deletions
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20
networking/tls.c
View File

@ -343,6 +343,20 @@ void FAST_FUNC tls_get_random(void *buf, unsigned len)
xfunc_die();
}
static void xorbuf3(void *dst, const void *src1, const void *src2, unsigned count)
{
uint8_t *d = dst;
const uint8_t *s1 = src1;
const uint8_t* s2 = src2;
while (count--)
*d++ = *s1++ ^ *s2++;
}
void FAST_FUNC xorbuf(void *dst, const void *src, unsigned count)
{
xorbuf3(dst, dst, src, count);
}
/* Nondestructively see the current hash value */
static unsigned sha_peek(md5sha_ctx_t *ctx, void *buffer)
{
@ -941,7 +955,6 @@ static void tls_aesgcm_decrypt(tls_state_t *tls, uint8_t *buf, int size)
memcpy(nonce, tls->server_write_IV, 4);
memcpy(nonce + 4, buf, 8);
buf += 8;
cnt = 1;
remaining = size;
@ -952,12 +965,12 @@ static void tls_aesgcm_decrypt(tls_state_t *tls, uint8_t *buf, int size)
COUNTER(nonce) = htonl(cnt); /* yes, first cnt here is 2 (!) */
aes_encrypt_one_block(&tls->aes_decrypt, nonce, scratch);
n = remaining > AES_BLOCK_SIZE ? AES_BLOCK_SIZE : remaining;
xorbuf(buf, scratch, n);
xorbuf3(buf, scratch, buf + 8, n);
buf += n;
remaining -= n;
}
//aesgcm_GHASH(tls->H, aad, tls->outbuf + OUTBUF_PFX, size, authtag);
//aesgcm_GHASH(tls->H, aad, tls->inbuf + RECHDR_LEN, size, authtag);
//COUNTER(nonce) = htonl(1);
//aes_encrypt_one_block(&tls->aes_encrypt, nonce, scratch);
//xorbuf(authtag, scratch, sizeof(authtag));
@ -1046,7 +1059,6 @@ static int tls_xread_record(tls_state_t *tls, const char *expected)
sz -= 8 + AES_BLOCK_SIZE; /* we will overwrite nonce, drop hash */
tls_aesgcm_decrypt(tls, p, sz);
memmove(p, p + 8, sz);
dbg("encrypted size:%u\n", sz);
} else
if (tls->min_encrypted_len_on_read > tls->MAC_size) {

1
networking/tls.h
View File

@ -81,6 +81,7 @@ typedef int16_t int16;
#define AES_BLOCK_SIZE 16
void tls_get_random(void *buf, unsigned len) FAST_FUNC;
void xorbuf(void* buf, const void* mask, unsigned count) FAST_FUNC;
#define matrixCryptoGetPrngData(buf, len, userPtr) (tls_get_random(buf, len), PS_SUCCESS)

9
networking/tls_aesgcm.c
View File

@ -11,15 +11,6 @@ typedef uint32_t word32;
#define XMEMSET memset
#define XMEMCPY memcpy
void FAST_FUNC xorbuf(void* buf, const void* mask, unsigned count)
{
word32 i;
byte* b = (byte*)buf;
const byte* m = (const byte*)mask;
for (i = 0; i < count; i++)
b[i] ^= m[i];
}
/* from wolfssl-3.15.3/wolfcrypt/src/aes.c */
static ALWAYS_INLINE void FlattenSzInBits(byte* buf, word32 sz)

2
networking/tls_aesgcm.h
View File

@ -4,8 +4,6 @@
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
void xorbuf(void* buf, const void* mask, unsigned count) FAST_FUNC;
void aesgcm_GHASH(uint8_t* h,
const uint8_t* a, //unsigned aSz,
const uint8_t* c, unsigned cSz,